Heating structure



June 28, 1960 J. l.. coLTEN ETAL 2,943,289

HEATING STRUCTURE INVENTOR. JERROLD L. COLTEN LEE M. WATSON ym a. 2,4%

AT TORNEY June 28, 1960 J. L. coLTEN ETAL 2,943,289

HEATING STRUCTURE Filed June 12, 1959 2 sheets-sheet 2 INVENTOR. LCOLTEN JERR [55E M. WATSON ATTORNEY United States Patent() 2,943,289HEATING STRUCTURE Jerrold L. Colten, South Bend, Ind., and Lee M.Watson, Three Oaks, Mich., assignors to' Welcraft Products Co., Inc.,New Carlisle, Ind., a corporation of Indiana Filed June 12, 1959, Ser.No. 819,960

14 Claims. (Cl. '338--208) The present invention relatesto a heatingunit and more particularly to an electrical heating structure adapted tobe embedded in the ground, driveways, runways, sidewalks, ramps, steps,roads, lloors and the like.

The primary object of the present invention is to provide a heatingstructure which will effectively and economically maintain .thetemperature of driveways, sidewalks, ramps and the like at a levelsulicient to melt ice and snow, and which can be easily and economicallymanufactured on a mass production basis using lmaterials and equipmentreadily available on the market.

` it isa further object of the invention to provide a heating structureof the aforesaid type having a series ofelectrical heating elementsections mounted on a wire mesh carrier, which can be fabricated with aminimum number' of voperations and which when completed is sturdy,durable, and convenient to handle, store and install. Y v

' A further object of the invention is to provide an electrical heatingunit which is adapted to be embedded in concrete or other materialforming driveways, sidewalks, roads and the like, and which has anelectrical resistance wire supported on and carried by a porous,flexible metal structure giving substantial protection to the wire whileit is being embedded in the concrete and facilitating effective anduniform distribution of heat from the wire throughout the surface of thedriveways and sidewalks overlying the unit.

Still another object is to provide a porous flexible unitary structurewhich can readily be placed or embedded in the ground or in concrete orasphalt in a single simple operation without any special skill orknow-how and without any special tools, equipment or fixtures.

Another object of the invention is to provide a reinforcing structurehaving an electrical heating wire distributed substantially throughout,Which permits the wire to be quickly laid and held in placeduringconstruction of driveways, walks and the like, eliminating thetedious and time consuming operation normally interrupting theconstruction work of laying and securing the individual strands orsections of wire in place.

Additional objects and advantages will become 4apparent from thefollowing description and accompanying drawings, wherein:

Figure 1 is a plan view of a strip of pavement or a section of adriveway illustrating our heating structure schematically in brokenlines;

Figure 2 is a fragmentary transverse sectional view taken on line 2-2 ofFigure 1 showing our heating structure embedded in a section of pavementsuch as a driveway;

Figure 3 is an enlarged fragmentary plan view of our new heatingstructure with portions broken away to better show the constructionthereof; Figure 4 is a fragmentary side elevational view of the heatingstructure shown in Figure 3;

Figure 5 is a vertical cross sectional view of the heating structuretaken lon line 5-5 of Figure 3;

2 Figure 6 is a vertical crossl sectional view of the heating structuretaken on line 6 6 of Figure 3; and

Figure 7 is an enlarged fragmentary cross sectional view of the heatingstructure taken on line 7--7 of Figure 3.

Referring more specifically to the drawings, numeral 10 designates awire mesh or screening carrier consistingv of longitudinal marginalwires 12 and intermediate wires- 14, each marginal wire being connectedwith an adjacent intermediate wire 14 at spaced intervals, as atportions 16 at which said` wires are iuterlocked by twisting. Theportions of the intermediate wire between the twisted portions 16 areoffset laterally at 18. The odset portions 13 are in turn twisted orintertwined with portions of adjacent intermediate wires 14 at 20. Thearrangement is such .that a regular substantially hexagonal patternisformed in the screen with adjacent intermediate wire portions 14interconnected at twisted portions 20 thereof regularly and uniformlythroughout the area of the screen. The twisted portions 16 and 20provide regularly spaced and arranged portions of reinforced characterfor increased strength. The wire may be of any suitable gauge,preferably galvanized and preferably sufficiently thin to be inherentlyflexible so that the screen can be rolled lengthwise into a coil ifdesired. The screen will normally be used in widths of twelve inches totwenty-four inches, and formed in convenient lengths, such as lengths ofve feet, ten feet, twelve feet, twenty feet, or any other length whichwill enable a user to complete a drive or heated area of any desiredlength l by using a combination of units of different standard lengths.

f An insulated electric resistance or-heating element 21 is carried bythe screening. The heating element consists of resistance wire 22encased within an insulating waterproof sheath 24 of ilexible materials,such as a thermoplastic material.` One thermoplastic materialparticularly well suited for the insulation 24 is a vinyl resin of thinwall construction which accommodates bending of the wire 22, iswaterproof, and constitutes a good electrical insulation. It will beunderstood, however, that any type of insulation coating, such asrubber, synthetic rubber, fabric coated or impregnated withwaterproofing material, or the like, may be utilized.

The insulated heating wire 21 is arranged in a plurality of straightsections28 spaced apart substantially uniformly and interconnected atcurved portions 30 adjacent opposite edges of the screen carrier. Eachlongitudinal section 28 is secured to the carrier at a plurality ofyspaced points along its length. The pattern in which the heating wireis arranged, and the points at which it is secured to the screen, mayvary somewhat from that shown as long as the spacing of the heating wiresections imparts thedesired heating characteristics to the unit and aslongY as a secure anchorage of theheating wire to the screen isobtained.

The manner in which the heating element is secured to the wire meshcarrier is of primary importance in the present invention and consistsof a plurality of spaced wire shafts 32 extending laterally acrosscarrier 10 and interlocking the heating element and carrier byalternately passing over a section o-f the element and thence under atwisted portion 20 as seen at numerals 34 and 36, respectively. The twoends 38 and 40 of the shaft are looped around or otherwise locked tomarginal wires 12 at twisted portions 16 in order -to secure the shaftsfirmly in place and to prevent displacement while the heating structureis being handled. The spacing of the shafts is preferably uniformthroughout most of the length of the structure; however, it is usuallydesirable to space the shafts somewhat closertogether near the ends ofthe structure to give additional support at the places in the structureVwhere displacement of the heating element from the carrier is mostlikely to occur. The Wire shafts are relatively stijf but aresufficiently exible that they may dip slightly in passing over theheating element sections and under twistedVv portions 20.

The carrier is preformed for receiving shafts 32 by bending outwardly orarching as seenl at numeral. 42, all of the twisted portions 2th in aparticular transverse row across the carrier,` the transverse rows ofpreformed arches being spaced from one another along the carrier,usually every three to tive transverse rows apart. As seen in ligure 3,the transverse rows of preformed twisted portions` near the left handend are spaced only one row apart whereas, for Vthe purpose ofillustration, the rows in the intermediate portion ofthe structure arespaced four rows apart. When the, heating element and shafts are ininterlocking relationship the sections of the heating element are bentslightly downwardly, as, seen in Figures 4, 5 and 6, ile. dippingslightly below the upper plane of the carrier into or adjacent the V ortrough-shaped connection 44 in and between connecting wires 14. Thedipping of the sections into the hexagonally shaped spaces prevents bothlateral and longitudinal slippage of the heating element sections. Whilethe sections of heating element are shown overlying the twisted portions20 in the intermediate transverse rows between shafts 32 they may beolfset slightly to the side one way or another without interfering withthe effective locking of the strands in the hexagonally shaped spaces.

T o facilitate the formation of a sturdy connection between the heatingelement sections 2S and the carrier, and to prevent lateral shifting ofthe sections on the carrier, intermediate wires 14 are preferablypre-bent to form in effect a trough-shaped structure forY receiving andretaining the wire sections. Wires 14 may be bent to hold the wiresections 2,8 only loosely, as shown at numeral 44 in Figure 7 or bent togrip or clamp the wire sections,` as illustrated at numeral 44", toretain the sections in place on the carrier without shafts 3-2. Thetrough-like structures for securing the heating element wire in placeare in rows and can be used with carriers having longitudinal andtransversely arranged wires. The troughs may be in either of these twosets of wires.

In fabricating the present heating structure, a section of the wiremeshcarriery is unrolled from a coil of the mesh, which lhas been preformedto provide arches 42 in twisted portions 20 of pre-selected transverserows, and cut to the desired length, for example ten, fifteen ortwenty-live feet. The heating elementv is then cut to length and laidback and forth in sections as shown in the drawing in a predeterminedpattern, generally in equal spaced parallel relationship. While thesections of the heating element are held in place on the carrier, a jigof suitable construction presses the strands downwardly at the placewhere the shaft 32 is to be inserted under arches 42 of a transverse rowof twisted portions 20, and the shaft of the correct length is insertedlengthwise from one si'de of the carrier. The shaft is then secured inplace by bending the ends of the shaft around marginal wire 12 with asuitable tool either manually or power operated. The jig is movedsuccessively along the carrier from one shaft inserting operation to thenext until the shafts` have been inserted at all the pre-selectedpositions. While in the. operation described the jig is moved, in someoperations the jig may be held stationary and the carrier moved relativeto the jig.

The opposite ends of the heating wire are connected to cold lead wires52, each preferably being of flexible character, though not necessarilyso, and provided with an insulating sheath 54 which may be ofthermoplastic material such as a vinylV res-in, or of any other suitabletype. The terminal portions of the wires 22 and 52 are connected by asuitable insulated electrical connector 56. The electrical leads 52 maybe connected to any suitable source of power 60 to complete a circuitunder the control of a switch 62. Y

In the use of the unit, as in a driveway, concrete 58 is rst poured inthe usual forms (not shown) to a depth of at least several inches andpreferably to a depth of one and one-half inches to two inches less thanthe desired depth or thickness of the pavement or slab, and is leveledthroughout in the conventional manner. Our unit of the desired length isthen laid upon the concrete. In the case of a driveway, the uni-ts arepositioned in the concrete at the part or parts where snow removal isdesired, and are laid the length of the driveway with the lead wires S2of each unit projecting laterally to the exterior of the form. In longdriveways a number of units may be required, the units being laid end toend in alignment throughout. The strip units are laid substantially flatso as to be substantially parallel with the plane of the finishedsurface of the pavement. Thereupon additional concrete is poured intothe form to cover the strip units and to Complete the slab or pavement.

The lead wires 52 of adjacent strip units or sections are then connectedto a source of power in a circuit under control of switch 62. Ifdesired, adjacent strip units or sections may constitute independentcircuits or they may be connected in series or in parallel relation. v

The combination of the Wire mesh carrier 10 and the multiple sections 28of insulated heating element 21 will not sinkv in the fresh or fluidconcrete of its own weight, and will not readily become displaced whenthe layer of concrete is poured thereon. Thus the strip units remain inthe desired plane at a selected spacing below the top Surface of thepavement 58 and substantially uniformly spaced therefrom throughout itslength.

The wires or heating elements 21 are maintained evenly or substantiallyuniformly spaced, or spaced in any other pattern having substantiallyuniform heating effect upon the pavement 58 in which they are embedded.The anchoring of thev heating Velement to. the wire screening places theinsulation sheath 24 of the heating elements in Contact with the wirescreen carrier at twisted or reinforcing portions 20 so as to transferheat to the wires making up the screen. These screen wires, being formedof metal, constitute good conductors of heat and serve to distributeevenly the heat generated by the heating element 21 throughout allportions of the carrier 10 and substantially uniformly throughout thearea of the pavement 58 in which the wire screen is embedded.

The strip unit is preferably placed with the heating element 21positioned below the carrier. In this manner the wire screen 10 servesIto protect theheater wire 2,1 from injury incident` to manipulation ofthe concrete as the top layer of the concrete is leveled by tools inlforming the pavement 5-8.` Thus the wire screen protects the heatingelement 21 from damage and at the same time serves to retainl theheating element in proper position in the fluid concrete. In addition toprotection of the heating wire,l the wire carrier 10 serves to reinforcethe concrete and to minimize cracking of the concrete. Avoidance ofcracking ofV the concrete also tends to protect the heating element` 21embedded therein against breakage.

Although the present description has been` directed primarily to aheating structure for installation in driveways, sidewalks, ramps,floors and the like, the structure can be effectively used withoutmodificationl to warm or heat lawns and garden areas,4 hot beds andother farm applications,l and walks and driveways constructed ofloosematerial such as gravel, crushed stone and the like. In installingthe present heating structure for these uses it is placed at a depth ofbetween two and six inches, i.e. a sufficient depth below the surface tohold the structure in place and to protect it from surface travel. Theterm pavemen will be used` in the claims to refer to and include all theusesl and purposes of the present heating structure mentioned herein.

While only one. embodiment of the invention has been illustrated anddescribed in detail herein, it is understood that changes in theconstruction may beA made without departing from the scope of -theinvention.

We claim:

1. A combination heating and reinforcing structure, comprising a carrierhaving marginal wires and lflexible longitudinally and diagonallyarranged wires forming laterally and longitudinally arranged hexagonalspaces throughout the carrier, the longitudinally arranged wires havingarched portions arranged in spaced transverse rows across said carrier,the arches of each transverse row extending in the same direction, aninsulated wire heating element arranged in longitudinal sectionsextending substantially the full length of the carrier and beingdisposed -between the longitudinal wires having said arches and on theside of said carrier on which said arches extend, said longitudinalsections being connected alternately at their ends, shafts at thetransverse rows of said arches extending under the arches and over thesections of heating element wire between said arches depressing saidelement wire into the respective hexagonal spaces and being secured attheir ends to the marginal wires, and flexible insulated electricalleads connected to the ends of said heating elementwire and projectingbeyond the edge of said carrier.

2. A combination heating and reinforcing structure,

comprising a carrier having marginal wires and ilexible longitudinallyand diagonally arranged wires forming laterally and longitudinallyarranged hexagonal spaces throughout the carrier, the longitudinallyarranged wires having arched portions arranged in spaced transverse rowsacross said carrier, the arches of each transverse -row extending in thesame direction, a heating element wire arranged in longitudinal sectionsextending substantially the fullv length of the carrier and beingdisposed between the longitudinal wires having said arches and on theside of said carrier on which said arches extend, said longitudinalsections being connected alternately at their ends, shafts at thetransverse rows of said arches extending under the arches and over thesections of heatingelement wire between said arches depressing saidelement wire into the respective hexagonal spaces and being secured attheir ends to the marginal wires, and electrical leads connected to theends of said heating element.

3. An electric heating structure, comprising a carrier having marginalwires and longitudinally and diagonally arranged wires forming laterallyand longitudinally arranged hexagonal spaces throughout the carrier, thelongitudinally arranged wires having arched portions arranged in spacedtransverse rows across said carrier, the arches of each transverse rowlextending in the same direction, an insulated wire heating elementarranged in longitudinal sections extending substantially the fulllength of the carrier and being disposed between the longitudinal wireshaving said arches and on the side of said carrier on which said archesextend, said longitudinal sections' being connected alternately at theirends, yand shafts at the transverse rows of said arches extending underthe arches and over the sections of heating element wire between saidarches and being secured at their ends to the marginal wires.

4. A heating structure, comprising a carrier having marginal wires andlongitudinally and `diagonally arranged y wires forming laterally andlongitudinally arranged hexagonal spaces throughout the carrier, thelongitudinally arranged wires having arched portions arranged in spacedtransverse rows across said carrier, the arches of each transverse rowextending in the same direction, an insulated wire heating elementarranged in longitudinal sections extending substantially the fulllength of the carrier and being disposed between the longitudinal wireshaving said arches and on the side of said carrier on which said archesextend, and shafts at the transverse rows of said arches extending underthe arches and over the sections of heating element wire between saidarches.

6 '5.'y A heatingjstructure, comprisingV a carrierl of longitudinallyand diagonally arranged wires, the longitudinally arranged wires havingarches arranged in spaced transverse .rows across said carrier, thearches of each transverse row extendingin the same direction, aninsulated wire heating element arranged in longitudinal sections andbeing disposed between the longitudinal wires having said arches and onthe side of said carrier on which said arches extend, and 4shafts at thetransverse rows of said `arches extending under the arches and over thesections of heating element wire between said arches.

6. A heating structure, comprising a carrier having marginal wires andlongitudinally and transversely arrangedv wires, .the `longitudinallyarranged wires having arched portions arranged in spaced transverse rowsacross said carrier, the `arches of each transverse row extending in thesame direction, an insulated wire heating element arranged inlongitudinal sections and being disposed between the longitudinal wireshaving said arches and on the side of said carrier on which said archesextend, and shafts at the transverse rows of said arches extending underthe arches and over the sections of heating element wire between saidarches and being secured at their ends to the marginal wires.

7. A heating structure, comprising a carrier of longitudinally andtransversely arranged wires, the longitudinally arranged wires havingarched portions arranged in spaced transverse rows across said carrier,the arches of each transverse row extending in the same direction, aninsulated wire heating element varranged in longitudinal sections andbeing disposed between the longitudinal wires having said arches and onthe side of said carrier on which said arches extend, and shafts at thetransverse rows of said arches extending under the arches and over thesections of heating element wire between said arches.

8. A heating structure, comprising a carrier of longitudinally andtransversely arranged wires and marginal wires connected to saidtransversely arranged wires, a heating element wire arranged inlongitudinal sections being disposed between the longitudinal wires, andshafts at spaced intervals along said carrier-extending transverselythereacross alternately under said longitudinal wires and over saidheating element sections and being secured at their ends to saidmarginal wires.

9. A heating structure, comprising a carrier of longitudinally andtransversely arranged wires, a heating element wire arranged inlongitudinal sections being disposed between the longitudinal wires, andshafts at spaced intervals along said carrier extending transverselythereacross alternately under said longitudinal wires and over saidheating element sections.

l0. A heating structure, comprising a carrier of longitudinally anddiagonally arranged wires, the longitudinally arranged wires havingarches arranged in spaced transverse rows across said carrier, thearches of each transverse row extending in ythe same direction, saiddiagonal wires having troughs extending in the direction opposite saidarches, an insulated wire heating element arranged in longitudinalsections and being disposed in said troughs, and shafts extending underthe arches and over the sections of heating element wire between saidarches.

ll. A heating structure, comprising a carrier having marginal wires andlongitudinally and transversely arranged wires, the longitudinallyarranged wires having arches arranged in spaced transverse rows acrosssaid carrier, the arches of each transverse row extending in the samedirection, said transverse wires having troughs extending in thedirection opposite'said arches, and an Insulated wire heating elementarranged in longitudinal sections land being disposed in said troughs,and shafts extending under the arches and over the sections of heatingelement wire between said arches .and being secured at their ends to themarginal wires.

12. A heating structure, comprising a carrier of longitudinally anddiagonally arranged wires, said diagonal 7 wiresv being bent betweensaid longitudinal wires to form troughs, and an insulated wire heating.element arranged in longitudinal sections and being disposed in'saidtroughs between the longitudinal wires, the portions of said diagonalwires forming said troughs engaging said element sections,

13'. A heating structure, comprising a. carrier having marginal wiresvand lc'zngitudinallyr and transversely arranged wires, said transversewires having troughs extending inwardly in the same. direction, and aninsulated wire. heating ,element arranged in longitudinal sectionsdisposed in said troughs,` the. portion of said transverse wires formingsaid troughs. gripping said element sections. 14. A heating structure,comprising -a carrier having of' said wires forming said troughsgripping said element sections.

References Cited in the file of this patent UNITED STATES PATENTS2,406,884 Mann et al Sept. 3, 1946 2,486,791 Mann et al. NOV. l, 19492,678,993 De Boer May 18, 1954

